Utility of ultrasound-guided near-nerve needle recording for lateral femoral cutaneous sensory nerve conduction study: does it increase reliability compared with surface recording?

INTRODUCTION: The aim of this study was to assess the reliability of a near-nerve needle recording technique in lateral femoral cutaneous nerve (LFCN) sensory nerve conduction studies (NCS). METHODS: Bilateral LFCN sensory nerve action potentials (SNAPs) were recorded from 10 healthy volunteers using surface and near-nerve needle recording electrodes. Absolute amplitudes were compared side-to-side in each subject and between the 2 techniques. RESULTS: Near-nerve needle electrode recording amplitude was significantly higher when compared with surface electrode recording (surface 9 µV, needle 58 µV; P < 0.0001), whereas side-to-side variability did not differ (surface 37%, needle 37%; P = 0.94). CONCLUSIONS: We propose that near-nerve needle recording is a simple technique to employ for clinicians with experience in ultrasound-guided needle placement, especially when evaluation is critical and responses are difficult to obtain. However, given the degree of side-to-side variability in healthy subjects, we recommend caution when interpreting side-to-side differences.

Sonographically guided costotransverse joint injections: a computed tomographically controlled cadaveric feasibility study.

OBJECTIVES: The primary purpose of this study was to describe and validate a novel sonographically guided costotransverse (CTRV) joint injection technique. METHODS: The bilateral T3-T10 CTRV joints of an unembalmed cadaveric specimen were localized using a 12-3-MHz linear array transducer. A 22-gauge, 2.5-in spinal needle was directed into the CTRV joint using an in-plane, lateral-to-medial approach under direct sonographic guidance. After needle placement, 3-dimensional computed tomographic (CT) images were obtained to assess the locations of the needle tips. This step was followed by injection of an iodinated contrast agent and repeated CT to assess the contrast flow pattern. An experienced musculoskeletal radiologist reviewed the CT images and assessed the accuracy of the injections (intra- or extra-articular). For intra-articular injections, a quantitative assessment of the percentage of injectate within the joint was performed. RESULTS: A total of 16 sonographically guided CTRV joint injections were completed on a single torso-pelvis specimen. Using our technique, 11 of 16 sonographically guided CTRV joint injections (68.8%) placed the contrast agent into the target joint. Quantitative analysis of the arthrograms showed 6 of 11 intra-articular injections (54.5%) with greater than 50% injectate within the joint capsule. CONCLUSIONS: To our knowledge, this study is the first to determine the feasibility of sonographically guided CTRV joint injections. Overall, 68.8% of injection attempts produced acceptable CTRV joint arthrograms, which compares favorably to a previously reported 76% accuracy rate for fluoroscopically guided CTRV joint injections. Although these injections are technically challenging, the use of sonographic guidance to perform CTRV joint injections is feasible and warrants further investigation to establish its role in the management of patients presenting with thoracic pain syndromes.